Previous studies suggested that the guidelines could improve survival, but there was no research assessing actual use of the guidelines.

"It was exciting to see such dramatic outcomes resulting from a simple two-hour training session with EMS personnel," study co-principal investigator Dr. Bentley Bobrow said in a news release from the U.S. National Institute of Neurological Disorders and Stroke (NINDS), which funded the study. Bobrow is a professor of emergency medicine at the University of Arizona.

In this study, he and his colleagues trained emergency medical service (EMS) agencies across Arizona in the brain injury guidelines. They then compared patient outcomes before and after implementation of the guidelines.

The 21,000 patients in the study suffered moderate, severe and critical head injuries.

Use of the guidelines did not affect overall survival rates, but did help double the survival rate of people with severe TBI. And their use tripled the survival rate in severe TBI patients who had to have a breathing tube inserted by EMS personnel.

The guidelines were also associated with an overall increase in survival to hospital admission, according to the study findings.

"We found a therapeutic sweet spot and showed that the guidelines had an enormous impact on people with severe TBI," said study leader Dr. Daniel Spaite, a professor of emergency medicine at the University of Arizona.

"The guidelines did not make a difference in the moderate TBI group because those individuals would most likely have survived anyway and, unfortunately, the extent of injuries sustained in many critical patients was too extreme to overcome," Spaite added.